Jestem Kanadyjką. And any of your male friends would say "Jestem Kanadyjczykiem".
Nominatives are: Kanadyjka and Kanadyjczyk.
Jestem Argentyńczykiem (male), Jestem Argentynką (female).
Or "Jestem z Argentyny" (I am from Argentina), "Pochodzę z Argentyny" (I come from Argentina).
It keeps surprising me how many similarities there are between Polish and Welsh. "And you" a ti (Cymraeg) a ty (Polish)
Well, "you"-sing forms beginning with "t" (and occasionally "d") are common throughout Indo-European languages.
Meksykanin is the Nominative, so as "jestem" needs Instrumental: Jestem Meksykaninem. Jestem Meksykanką for a woman (but the Nominative is Meksykanka).
As the contrasting and "a" is used in the Polish and there is no direct translation would not "I am American are you" be more appropriate as it is a question?
I'm English. So why not I'm American.. or as in earlier lesson.. I'm British.?
A man should say "Jestem Gwatemalczykiem" (Nom: Gwatemalczyk), a woman should say "Jestem Gwatemalką" (Nom: Gwatemalka).
As we rarely encounter people from Guatemala in Poland, somehow a safer version (in my opinion) would be to say "Jestem/Pochodzę z Gwatemali" (I am/I come from Guatemala). With countries about which we don't talk much, Polish people may not be sure how to create a demonym (a noun for a person from that country).
So, in sentences of this nature, it is not possible to use "Jestem" + adjective? In English, it is natural for me to say "I am English", rather than "I am an Englishman", but "Jestem angielski" would be wrong? Are these adjectives only used for languages?
Not only for languages, just as adjectives. "angielski film" = "an English movie", for example.
But no, they absolutely can't be used like "Jestem angielski". A demonym is always a noun in Polish.
Why is I am American and you wrong? Also how do I say I am a New Zealander?
"I am American, and you?" should be OK when speaking/writing English IMHO. As I noted above, it is more natural for me to say "I am English" than "I am an Englishman". That is a difference from Polish.
Being a New Zealander is different again; I don't think you could say "I am New Zealanderish", except perhaps as a joke.
"I am American" works, we just use "an American" because it's correct and also it's visible then why we want a noun in Polish.
So, "New Zealand" = "Nowa Zelandia", with a male denonym "Nowozelandczyk" and a female "Nowozelandka". So for you it's "Jestem Nowozelandczykiem".
A safe way can always be to say "[Jestem/Pochodzę] z Nowej Zelandii".
It would seem so; it seems to me that using "ty" means you already know the person quite well, so you would have gotten past the stage of working out each other's nationality a long time ago.
Maybe it's OK for children?